Molecular Simulation for Liquid Vapour Equilibria of Ethylene, R1132a, R1132(E) and R1123

摘要

Molecular dynamic simulation is a powerful tool to predict various physical properties of new refrigerants,especially for un-synthesized new substances and for very low-temperature conditions that are difficult toexperiment with. To improve the simulation accuracy for olefin-group-refrigerants with very low globalwarming potentials, non-bonded force field parameters of atoms adjacent to an unsaturated bonding arecarefully validated with the measured properties and a quantum chemistry calculation in this study. Theprediction results of the liquid-vapor equilibrium system of ethylene and its derivatives (CH_2=CH_2, CH_2=CF_2,trans-CHF=CHF, CHF=CF_2) are compared between a well-known general force field OPLS-AA/L and amodified. Those parameters presented by Raabe (2012) are rather closer to the modified one. With the modifiednon-bonded force field parameters, consistency in the prediction results of saturated liquid-vapor densities,saturation pressure, and surface tension is improved; however, intermolecular interactions between dimers arenot yet precisely represented in all orientations.